Vehicle traffic control systems, such as air traffic control systems, track positions and velocities of vehicles and help manage the trajectories of the vehicles. Vehicle traffic control may be based on radar surveillance, supplemented more recently with cooperative radio surveillance techniques, such as automatic dependent surveillance-broadcast (ADS-B). A vehicle may determine its own position, using, for example, a Global Navigation Satellite System (GNSS) configured to transmit positioning signals from multiple satellites to a receiver on the vehicle. The vehicle may periodically broadcast its position via surveillance signals at a radio frequency. Other vehicles and base stations may receive and read the surveillance signals to determine a location for the vehicle. Vehicle position data may be provided to a variety of other applications that serve functions such as traffic situational awareness, traffic alert, and collision avoidance, for example.